The present invention relates to an air conditioning apparatus such as an air conditioner, a dehumidifier and an air purifier, and more particularly to an air conditioning apparatus in which a cross flow fan is mounted to be used as a blowing means.
Hereafter, a description will be made of an air conditioning apparatus, such as an air conditioner, a dehumidifier and an air purifier, in which a conventional cross flow fan is mounted. An example of the conventional cross flow fan entitled xe2x80x9cIndoor Unit for Air Conditionerxe2x80x9d is disclosed in Japanese Unexamined Patent Publication No. Hei 11-83062, for instance. FIG. 50 is a longitudinal cross-sectional view of the main body of an air conditioning apparatus disclosed in Japanese Unexamined Patent Publication No. Hei 11-83062. FIG. 51 is a perspective view of the impeller of a conventional cross flow fan. FIG. 52 is a longitudinal cross-sectional view of the cross flow fan of FIG. 51. FIG. 53 is a cross-sectional view of a vane shown in FIG. 52. FIG. 54 is a diagram illustrating the frequency characteristic of noise of the air conditioning apparatus in which the conventional cross flow fan is mounted.
With referring to FIGS. 50, 51 and 52, the conventional cross flow fan is formed by an impeller 101, a guide wall 102, a stabilizer 103, and a motor 104. The impeller 101 is formed by two or more units 110a which are connected in the direction of the shaft, each unit being formed by a plurality of vanes 101b and a ring 101c for supporting the plurality of vanes. The guide wall 102 surrounds the impeller 101 in such a manner as to cover one side of the peripheral surface of the impeller 101. The stabilizer 103 is disposed in such a manner as to face the guide wall 102. The motor 104 rotates and operates the impeller 101 as indicated by an arrow J.
According to the air conditioning apparatus in which the thus configured conventional cross flow fan is mounted, as shown in FIG. 50, air is sucked in through a detachable front facing grill and a detachable top facing inlet grill, then dust is removed from the air by using a filter, and thereafter the air is heated or refrigerated by means of a heat exchanger which is formed in such a manner as to surround the impeller 101. Heat-exchanged air after passing through the heat exchanger is sucked into the impeller 101, passes through a row of vanes on the side of the heat exchanger, and then is blown off again through a row of vanes on the side of an air outlet. Then, the air is blown off through the air outlet to the room by blowing-direction changing vanes, including up/down vanes and left/right vanes, changing the blowing direction of the air. Thus, the room is air-conditioned.
With referring now to the vane 101b in a cross-sectional shape shown in FIG. 53, a reference numeral A20 denotes a tip of a vane""s peripheral end portion A2 in the shape of a circular arc of the vane 101b. A reference numeral A10 denotes a tip of a vane""s internal circumferential end portion A1 in the shape of a circular arc of the vane 101b. A reference mark O denotes the center of the rotating shaft of the impeller 101, and a reference numeral 1 denotes the center of a camber line P0 formed into a single circular arc of the vane 101b. A reference numeral P2 denotes a pressure face of the vane 101b on a side facing the direction of rotation of the impeller, and a reference numeral P3 denotes a suction surface opposing to the pressure face P2. O-A20 indicates a first straight line connecting the tip of the vane""s peripheral end portion A20 of the vane 101b and the center O. O1-A20 indicates a second straight line connecting the tip of the vane""s peripheral end portion A20 of the vane 101b and the center O1 of the camber line P0. Further, a reference mark n denotes a first perpendicular of the first straight line O-A20 to the tip of the vane""s peripheral end portion A20, and a reference mark m denotes a second perpendicular of the second straight line O1-A20 to the tip of the vane""s peripheral end portion A20. An exit angle xcex22 is an acute angle formed by the first perpendicular and the second perpendicular.
With referring to the cross flow fan, for example, by expanding the outside diameter xcfx86D2 of the impeller 101 in a similar shape, the flow rate is increased and the noise level is lowered. However, if the flow rate is increased and the noise level is lowered in such a manner, singular noise S1 is generated in a low frequency range as shown in the diagram illustrating the frequency characteristic of noise of FIG. 54. In addition to that, there may be a case where the noise level at the same flow rate is increased and a resultant atmosphere to the ear is made worse. For that reason, according to the conventional cross flow fan, the singular noise S1 is tried to be reduced by setting the exit angle xcex22 of the vane 101b to 23 degrees or less. Furthermore, by setting the exit angle xcex22 to 18 degrees or more, the noise level at the same flow rate is lowered and a resultant atmosphere to the ear is controlled not to be aggravated.
Furthermore, by forming the vane 101b such that tmax/tmin =1.3xcx9c1.5, a blowing performance at a high flow rate may be obtained, where tmax denotes a maximum thickness of the vane 101b and tmin denotes the thickness of the vane""s peripheral end portion, which is the thickness of a portion of the vane 101 excluding a roundish portion at a mounting end of the vane 101 on the vane""s peripheral side. In addition to that, this also allows to obtain an interior unit of an air conditioner which has less opportunities of generating the singular noise in a low frequency range.
However, according to an air conditioning apparatus using the conventional cross flow fan disclosed in Japanese Unexamined Patent Publication No. Heill-83062, in the case that the suction resistance of the impeller 101 becomes high due to a decrease in the fin pitch of the heat exchanger, or dust accumulated on the filter, a circulating vortex C1 caused near the stabilizer 103, which is a typical phenomenon of a cross flow fan, may develop from a solid circle to a broken bold circle. Then, air after passing through the heat exchanger flows towards a cross flow vortex having a lower pressure, and then sucked into the impeller 101 as indicated by the arrow of FIG. 50. As a result, in an area F1, the flow of air may be detached from the vane 101b, and then an air turbulent vortex G1 may be generated at a rear portion of the vane 101b. Consequently, as shown in the diagram illustrating the frequency characteristic of noise of FIG. 54, there may be a case where the singular noise Sm having a frequency width fs is generated in a low frequency range of around 40 to 80 percent of the generation frequency of the rotation noise (NZ sound) depending upon the number of vanes Z and the rotational frequency N [r.p.m] of the impeller 101. For that reason, a jarring noise other than the rotational noise may be generated, which produces an aggravated atmosphere to the ear, and this has been a problem.
Furthermore, because the vane""s exit angle xcex22 is reduced, thereby narrowing a vane""s distance, when the flow of air passes between vanes, a resistance occurs. As a result, the shaft output for operating the impeller is increased, which increases the power consumption of the motor.
Hence, the present invention has been devised to solve the above described problems, and an object is to obtain an air conditioning apparatus which provides a favorable atmosphere to the ear and saves energy by controlling noise not to be aggravated even if the suction resistance of the impeller becomes high due to such as noise and dust during its operation, and further, by minimizing the generation of the singular noise in a low frequency range and the rotation noise, and minimizing the power consumption of the motor.
An air conditioning apparatus according to a first invention is characterized by having a cross flow fan which includes an impeller being formed by a plurality of vanes and a ring for supporting the plurality of vanes, and a heat exchanger. Then, the cross flow fan includes a nozzle portion which is formed by a stabilizer and an outlet, and a guide wall. A ratio H/xcfx86D2 of a height H of a main body of the air conditioning apparatus to an outside diameter xcfx86D2 of the impeller is 2.2 or above and 3.0 or below.
An air conditioning apparatus according to a second invention is characterized by an impeller of a cross flow fan in which a vane""s exit angle xcex22 is between 23 degrees and 30 degrees.
An air conditioning apparatus according to a third invention is characterized by an impeller of a cross flow fan in which a ratio tm/t2 of a maximum thickness tm of the vane of the impeller of the cross flow fan to a minimum thickness t2 of the vane is at least 1.5 or above and 3.5 or below when the minimum thickness t2 is a diameter of a peripheral end portion of the vane in a shape of a circular arc so as to reduce singular noise generated in a frequency range lower than that of rotation noise, and a thickness of the vane is gradually varied.
An air conditioning apparatus according to a fourth invention is characterized by an impeller of a cross flow fan in which a maximum thickness of a vane of the impeller of the cross flow fan is between 0.9 mm and 1.5 mm when a minimum thickness t2 of the vane of the impeller of the cross flow fan is between 0.2 mm and 0.6 mm and the minimum thickness t2 of the vane is a diameter of a peripheral end portion of the vane in a shape of a circular arc.
An air conditioning apparatus according to a fifth invention is characterized by an impeller of a cross flow fan in which the maximum thickness of the vane of the impeller of the cross flow fan is between 0.9 mm and 1.5 mm when the minimum thickness t2 of the vane of the impeller of the cross flow fan is between 0.2 mm and 0.6 mm and the minimum thickness t2 is the diameter of the peripheral end portion of the vane in the shape of the circular arc.
An air conditioning apparatus according to a sixth invention is characterized by an impeller of a cross flow fan in which the vane is formed into a shape of an edge obtained by cutting the vane along a circle passing through a peripheral end portion of the vane where a center of the circle is a center O of a rotating shaft of the impeller.
An air conditioning apparatus according to a seventh invention is characterized by an impeller of a cross flow fan in which the vane is formed into a shape of an edge obtained by cutting the vane along a circle passing through the peripheral end portion of the vane where a center of the circle is a center O of a rotating shaft of the impeller.
An air conditioning apparatus according to an eighth invention is characterized by an impeller of a cross flow fan in which the plurality of vanes is fitted with an irregular space between the vanes in pitch.
An air conditioning apparatus according to a ninth invention is characterized by an impeller of a cross flow fan in which the plurality of vanes of the impeller of the cross flow fan is fitted with an irregular space between the vanes in pitch.
An air conditioning apparatus according to a tenth invention is characterized by a cross flow fan in which the stabilizer is formed at a lower front portion of the air conditioning apparatus in such a manner that an acute angle formed by a straight line, and a horizontal line is between 30 degrees and 70 degrees when the straight line connects a closest point of the stabilizer to the impeller of the cross flow fan to a center O of a rotating shaft of the impeller and a horizontal line and the horizontal line passes through the center O of the rotating shaft of the impeller.
An air conditioning apparatus according to an eleventh invention is characterized by the stabilizer which is formed in such a manner that an acute angle formed by two straight lines is between 15 degrees and 40 degrees when the two straight lines connect a center O of the impeller of the cross flow fan, respectively, to a closest point of the stabilizer to the impeller of the cross flow fan and to a lower portion of the stabilizer.
An air conditioning apparatus according to a twelfth invention is characterized by a cross flow fan in which the guide wall is formed at an upper rear portion of the air conditioning apparatus in such a manner that an angle xcex83 formed by a straight line and a horizontal line is between 35 degrees and 80 degrees when the straight line connects a closest point of the guide wall to the impeller of the cross flow fan and a center of a rotating shaft of the impeller and the horizontal line passes through the center O of the rotating shaft of the impeller,
An air conditioning apparatus according to a thirteenth invention is characterized by an impeller of a cross flow fan in which a shape of a peripheral end portion of the vane extends to a peripheral side of the impeller in a shape of an inclining parallelogram forward in a direction of rotation of the impeller, but the shape is not projecting outside a periphery of the ring for supporting the plurality of vanes, in a cross-sectional view at right angles to a line of a rotating shaft of the impeller of the cross flow fan.
An air conditioning apparatus according to a fourteenth invention is characterized by an impeller of a cross flow fan in which two vertexes of a peripheral end portion of the vane facing a peripheral side of the impeller are formed in a fixed shape of R when the vertexes extend to the peripheral side of the impeller in a shape of parallelogram.
An air conditioning apparatus according to a fifteenth invention is characterized by an impeller of a cross flow fan in which each of the plurality of vanes of the impeller of the cross flow fan is inclined by a fixed angle to a rotating shaft of the cross flow fan.
An air conditioning apparatus according to a sixteenth invention is characterized by an impeller of a cross flow fan in which a peripheral end portion of the vane of the impeller of the cross flow fan is formed by an elastic body.